1. Field of the Invention
The present invention relates to a pilot solenoid valve that is installed on a manifold base to drive the valve body of a main valve using pilot fluid supplied or ejected through pilot valves driven by a solenoid, and that switches the output opening of the main valve between a supply opening and an ejection opening for communication.
2. Description of the Related Art
Pilot solenoid valves that include a main valve installed on a manifold base and pilot valves attached to the main valve to drive the valve body of the main valve using a pilot fluid which is supplied or ejected through the pilot valves, and that switches the output opening of the main valve between a supply opening and an ejection opening for communication are well known and need not be illustrated here.
If such well-known pilot solenoid valves are used in a very humid working environment, for pilot valves that have an electrical section, the energization system must be protected to prevent accidents that could be caused by water. It is difficult and expensive, however, to make only the pilot valves attached to the main valve and the energization system water proof or moisture-proof. Therefore, so it is simpler and more effective to cover all the valves including a large number of the main valves arranged on manifold bases to protect them from water.
When, however, the pilot solenoid valve is waterproof, the cover must be removed to disable the overall waterproof function each time maintenance or inspection of the main or pilot valves is carried out or a defective part is replaced even if said maintenance or inspection involves parts other than the pilot valves, which do not require a waterproof function. This might cause some troubles and is also a problem that makes maintenance and inspection cumbersome. In addition, the pilot solenoid valve normally includes a manual operation section that allows the main or pilot valves to be manually opened and closed when power supply is interrupted or the valves becomes defective. In such a case, the cover must also be removed to disable the overall waterproof function.